Yup, that’s So and So’s track … and what story does it tell?
Concept Illustrated: True Track (Canine toe pad)
The idea: Demonstrate the creation of, and difference between apparent and true track, as the track is being made.
The “true track” (term from Tom Brown, Jr.) is the track created by all surfaces of the foot in contact with the ground, up until the bottom surface of the foot itself has stopped compressing. It does not include the portions of the track created by pressure against the wall.
Another definition: “…the track bottom respective to the substrate, which was in direct contact with the track-maker’s foot (Gatesway, 2003).”: Falkingham, P.L. 2016. Glossary: “true track…” in P.L. Falkingham, D. Marty, and A. Richter (eds.), Dinosaur Tracks: The Next Steps. Indiana University Press, Bloomington, Indiana.
Both “true” and “apparent” track are subjective terms. The top outer most outline of the track (apparent track) is often used as a measurement of its dimensions. For a useful discussion of this issue read: Falkingham, P.L. 2016. Applying objective methods to subjective track outlines; chap. 4 in P.L. Falkingham, D. Marty, and A. Richter (eds.), Dinosaur Tracks: The Next Steps. Indiana University Press, Bloomington, Indiana.
This apparent outline is created during a process that begins the moment the foot contacts the earth … Continues while weight is applied … During the expansion of the foot outwards against the track wall … And up until the last contact between foot and earth … Perhaps even a bit further. It often includes the top of the ridge of soil pushed out and away from the foot as it rolls down onto the ground.
It can be an inaccurate measurement because it reflects the displacement of soil after the foot leaving the track has been distorted by weight and force. It gets worse … After the foot has fully landed there can still be movement of the soil away from the edges of the foot … And the foot is still deforming and displacing soil. Measured this way, the dimensions of the track will include some of those distortions. These can vary with every step and are unlikely to be consistent.
Seeing and measuring tracks by use of the true track will give one a more accurate idea of actual foot size, be more consistent, and keeps everyone using the same measurements. Variations in track measurements collected with this method are still possible, but will be reduced.
Finding the true track, well there’s the rub, if for no other reason than it can be a very fine distinction.
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Concept Illustrated: A Simple Tire Track and Direction of Travel
The idea: Tires leave tracks. However, without knowing which details to examine it can be confusing to determine the direction that tire was traveling.
In the clip inserted above the goal is to give the observer a chance to watch one of the most obvious parts of a tire track being formed, and a couple of hints about where to look to figure out which way it was traveling.
The following version has a little more detail…
Notes about reading tire tracks: Haven’t studied this but have observed a few things, variables one might consider.
– “How nice! They drove back the same way and the two tire trails are so close!”
– What differences can you see between the tracks left by a trailer and the vehicle pulling it? (Turns make this easy)
– Can you find a nick that’s repeated? What is the distance between those two nicks a measure of?
– What is the length of the tire’s footprint? Where along that vehicle’s trail to make a quick estimate? Is this measurement useful?
– How do changes in forward motion show up?
– How does inflation pressure affect the track?
– What’s differences show in a tire track created while maintaining motion and one left while coasting? (Hint: Trailers) Acceleration?
– Do the angles (relative to direction of travel) of the front and rear-facing edges of a tread segment affect the track?
– Do the treads on a tire interact with the substrate the same way as lugs on a Vibram shoe sole?
– If the pressure releases in the wave (in the video clip it forms below white arc) indicate force applied to maintain or alter motion, can they indicate direction of travel?
– What about weight?
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The Other Concepts:
Page: How To Find and See Tracks … Ways to reveal hard to see tracks and details
Predicting where the next track will be…
Dust Compressions (Dull on Shiny by Canine Toe Pad)
Controlling Lighting to Increase Visibility of Tracks
Track on ‘Bare’ Rock (Red Fox Front Foot)
Using Stone Rolls to Find Tracks
The Tracking Stick
Page: Track Features … The story is revealed by the details
Pressure Against the Track Wall (Canine Toe Pad)
The Wave, Simple?
The Ridge Between Canine Front Toes
The Layer of Sand in Contact With The Foot